JP2018129334A - Electromagnetic solenoid and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute an electromagnetic solenoid that enables good operation of a plunger even when foreign matter enters between the inner periphery of a cylindrical member and the outer periphery of the plunger.SOLUTION: An outer peripheral surface 21S of a plunger 21 disposed inside a cylindrical member 23 includes a columnar outer wall region 21Sa centered on the axis and a roughened surface region 21Sb composed of a large number of concave portions b recessed with the outer wall region 21Sa as a reference. The concave portion b is a spherical inner surface having a predetermined diameter and at least some of the plurality of concave portions b overlap each other, such that the depression of the concave portion b with reference to the outer wall region 21Sa is formed as a foreign matter accommodating portion T having a depth E larger than a preset particle diameter G of a foreign matter a.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electromagnetic solenoid that linearly operates a plunger fitted in a cylindrical member by energizing an exciting coil, and a method for manufacturing the electromagnetic solenoid.

  As an electromagnetic solenoid, in Patent Document 1, a plunger is disposed in an internal space of a cylindrical tubular member (in the literature, a plate), and the position of the plunger is determined by energizing an excitation coil disposed outside the tubular member. The configuration is described.

  This patent document 1 opens and closes a valve body by operation of a plunger, and both end portions of the plunger are formed into a tapered shape by chamfering. By chamfering the plunger in this way, generation of wear powder during operation of the plunger is suppressed.

  In Patent Document 1, a plurality of holes are formed on the outer periphery of the plunger, or a cylindrical material is used for the plunger, and a plurality of penetrations that connect the inner periphery and the outer periphery are formed. Configured to capture.

  In Patent Document 2, an exciting coil is arranged on the outer periphery of a cylindrical member (in the literature, a spool), a plunger is fitted into the cylindrical member, an armature is provided in the plunger, and the exciting coil is energized. A configuration for actuating the plunger is described.

  In Patent Document 2, an uneven surface is formed on the outer periphery of the plunger by shot peening or sand blasting, thereby making the recess into an oil sump or suppressing the surface-to-surface contact between the plunger and the cylindrical member. .

  In Patent Document 3, a needle (movable in the axial direction) is accommodated in a valve case, and a plunger (armature in the document) integrally formed with the needle is fitted to a cylindrical member (stator core in the document) integrally formed with the valve case. A flow control valve having a return spring in which an exciting coil (solenoid coil in the literature) is arranged in a region surrounding the cylindrical member and urges the needle in the protruding direction is described.

  In this patent document 3, by energizing the exciting coil, the plunger is operated against the urging force of the return spring, and the fluid can be controlled by the needle. In particular, a plurality of annular oil grooves and a plurality of axial grooves are provided on the outer periphery of the plunger (armature).

  Since the plurality of axial grooves provided in this manner function as a foreign matter discharge passage, wear powder that convects to the spring accommodating chamber etc. is discharged through the foreign matter discharge passage, and the sliding failure of the needle due to the foreign matter is prevented. Suppress.

Japanese Patent Laid-Open No. 2015-212556 JP 2010-2112016 A JP 2007-56964 A

  As an electromagnetic valve that supplies hydraulic oil to hydraulic equipment of a vehicle, a configuration including a spool that controls the flow of hydraulic oil and an electromagnetic solenoid that linearly operates the spool is imagined.

  In an electromagnetic valve configuration in which an electromagnetic solenoid has a plunger made of a magnetic material movably disposed inside a cylindrical member in which an excitation coil is arranged on the outer periphery, the plunger and the spool are arranged adjacent to each other for smooth operation of the plunger. For the purpose of performing, a configuration in which a part of the hydraulic oil from the spool is fed into the gap between the cylindrical member and the plunger is often employed.

  Here, considering that the oil in the engine oil pan (engine oil) is used as the working oil, if the distance between the inner periphery of the cylindrical member and the outer periphery of the spool is small in the electromagnetic valve, it is included in the engine oil. The fine particles may enter between the inner periphery of the cylindrical member and the outer periphery of the plunger, thereby hindering the smooth operation of the plunger. In particular, in a vehicle equipped with a diesel engine as an engine, carbon particles generated at the time of combustion are mixed in engine oil, so that the sliding resistance of the plunger is increased to hinder the operation and an improvement is desired.

  Further, in the electromagnetic solenoid, wear powder is generated by contact with the inner surface of the cylindrical member during operation of the plunger, and this wear powder may become a foreign matter and hinder the operation of the plunger.

  Considering the situation in which foreign matters such as carbon particles and wear powder are included in the hydraulic oil in this way, in the technique described in Patent Document 1, the clearance between the inner periphery of the cylindrical member and the outer periphery of the plunger is constant. Improvement of malfunction of the plunger due to foreign matter cannot be expected. Further, in the technique described in Patent Document 2, the depth of the recess formed on the plunger surface does not take into account the particle size of the foreign matter contained in the hydraulic oil, so that the linear operation of the plunger is impaired. It was also possible.

  Furthermore, in the technique described in Patent Document 3, it is possible to discharge the foreign matter that has entered between the inner periphery of the cylindrical member and the outer periphery of the plunger, but the region excluding the annular oil groove and the axial groove. Then, since the clearance between the inner periphery of the cylindrical member and the outer periphery of the plunger is constant, it is conceivable that a malfunction may be caused by foreign matter contained in the hydraulic oil.

  For these reasons, there is a need for an electromagnetic solenoid that enables satisfactory operation of the plunger even when foreign matter enters between the inner periphery of the cylindrical member and the outer periphery of the plunger, and a method for manufacturing the same.

A feature of the present invention is that a cylindrical member, a plunger made of a magnetic material disposed inside the cylindrical member so as to be movable along the axial center of the cylindrical member, and the plunger by applying a magnetic force. An excitation coil that operates along the axis of the cylindrical member,
The outer peripheral surface of the plunger has a cylindrical outer wall region centering on the axis of the plunger, and a rough surface region composed of a large number of recesses recessed with respect to the outer wall region.
The recess has a spherical inner surface with a predetermined diameter, and at least a part of the plurality of recesses is formed to overlap, so that the recess of the recess with respect to the outer wall region is an inner periphery of the cylindrical member. The foreign material container is formed as a foreign material container having a depth larger than a preset particle size of the foreign material entering the gap between the surface and the outer peripheral surface of the plunger.

According to this characteristic configuration, when a foreign object enters between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the plunger, the foreign object fits into the foreign object container that forms the rough surface area in the plunger. The foreign matter does not contact the inner periphery of the cylindrical member and the outer periphery of the plunger at the same time. Thereby, sliding resistance does not increase by a foreign material, and operation | movement of a plunger is not impaired. In this configuration, since the outer peripheral surface of the plunger is composed of a smooth cylindrical outer wall region centered on the plunger shaft core and a rough surface region made up of a large number of recesses, the plunger serves as the shaft core. When operating linearly in the direction along, the outer wall region of the plunger is guided by the inner peripheral surface of the cylindrical member, and the height of the plunger in a state where the axis of the plunger is aligned with the inner peripheral axis of the cylindrical member. Movement with accuracy is possible.
Therefore, an electromagnetic solenoid is provided that allows the plunger to operate satisfactorily even when foreign matter enters between the inner periphery of the cylindrical member and the outer periphery of the plunger.

  As another configuration, the foreign substance container may reach at least one end of the plunger by being continuous in at least a direction along the axis.

  According to this, when a foreign substance is fitted in the foreign substance storage part, it is possible to move the foreign substance in a direction along the axial center and discharge it from one end of the plunger, thereby further improving the operation of the plunger. Realize.

  As another configuration, a gap between the inner peripheral surface of the cylindrical member and the outer wall region of the plunger may be set larger than the particle size.

  According to this, even when a foreign object enters between the inner wall surface of the cylindrical member and the outer wall region of the plunger, there is no inconvenience that the foreign material contacts the inner wall surface of the cylindrical member and the outer wall region of the plunger at the same time. . This achieves better operation of the plunger.

A feature of the present invention is that a cylindrical member, a plunger made of a magnetic material disposed inside the cylindrical member so as to be movable along the axial center of the cylindrical member, and the plunger by applying a magnetic force. An electromagnetic solenoid comprising an exciting coil that operates along the axis of the cylindrical member;
Due to shot peening of the base material, the plunger does not collide with the projecting material, and the outer wall region is a columnar shape centering on the axis of the plunger, and the projecting material collides with the outer wall region to make a large number of depressions. A rough surface region having a concave portion, and formed on the outer surface,
The foreign substance container is formed by overlapping at least a part of the plurality of concave portions.

According to this characteristic configuration, by performing shot peening that causes the projection material to collide with the base material of the plunger, the region where the projection material does not collide is made the outer wall region, and rough areas are formed by the numerous recesses formed by the collision of the projection material. Can be a surface area. That is, the outer peripheral surface of the plunger can be formed with a smooth columnar outer wall region centered on the shaft core and a foreign substance containing region in which a large number of concave portions are overlapped.
As a result, when a foreign object enters between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the plunger, the foreign object can be fitted into the foreign material container that forms the rough surface area in the plunger. A foreign object does not contact the inner periphery of a cylindrical member and the outer periphery of a plunger simultaneously. Further, the sliding resistance is not increased by the foreign matter, and the operation of the plunger is not impaired.

Furthermore, in this configuration, since the outer peripheral surface of the plunger is composed of a smooth cylindrical outer wall region centered on the plunger shaft core and a rough surface region made up of a large number of recesses, the plunger serves as the shaft core. When operating in the direction along, the outer wall region of the plunger is guided by the inner peripheral surface of the cylindrical member, and the plunger can be moved in a state in which the axial center of the plunger coincides with the inner peripheral axis of the cylindrical member. Become.
Therefore, a method for manufacturing an electromagnetic solenoid is provided that allows the plunger to operate satisfactorily even when foreign matter enters between the inner periphery of the tubular member and the outer periphery of the plunger.

  As another configuration, the foreign substance accommodating portion may reach at least one end portion of the plunger by forming adjacent concave portions so as to be aligned at least in the direction along the axis.

  According to this, when a foreign substance is fitted in the foreign substance storage part, it is possible to move the foreign substance in a direction along the axial center and discharge it from one end of the plunger, thereby further improving the operation of the plunger. Realize.

It is sectional drawing of the electromagnetic valve which has a spool in a 1st position. It is sectional drawing of the electromagnetic valve which has a spool in a neutral position. It is sectional drawing of the electromagnetic valve which has a spool in a 2nd position. It is an expanded sectional view of the crevice part of the peripheral surface of the plunger of this embodiment, and a rear yoke. It is an enlarged view which shows the outer wall area | region and rough surface area | region of the plunger of this embodiment. 6 is an enlarged cross-sectional view of Comparative Example 1. FIG. 10 is an enlarged cross-sectional view of Comparative Example 2. FIG. 6 is a graph showing hysteresis of a current value in Comparative Example 1. 10 is a graph showing hysteresis of a current value in Comparative Example 2. It is a graph which shows the hysteresis of the electric current value of this embodiment. It is a graph which clarifies the difference of hysteresis. It is sectional drawing of the electromagnetic solenoid unit of another embodiment (a).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, an electromagnetic valve V is configured by including a valve unit 10 and an electromagnetic solenoid unit 20.

  In this configuration, the electromagnetic valve V is supported by the block-shaped member 1 by fitting the valve unit 10 into a hole-shaped portion of the block-shaped member 1 such as an engine cylinder block and fastening the bracket 14 of the valve unit 10 with the fastening bolt 2. Is done.

  The electromagnetic valve V controls supply / discharge of hydraulic fluid to / from a valve opening / closing timing control device that sets the opening / closing timing (valve timing) of an intake valve and an exhaust valve of a vehicle engine, a double-acting hydraulic cylinder of the vehicle, and the like.

  In this embodiment, lubricating oil of an engine oil pan is used as hydraulic oil. The block-like member 1 has a supply flow path 1p through which hydraulic oil is supplied from the hydraulic pump P, a first flow path 1a and a second flow path 1b communicating with the hydraulic actuator, and a discharge flow path for returning the hydraulic oil to the oil pan. 1d is formed.

〔Valve unit〕
As shown in FIGS. 1 to 3, a cylindrical sleeve 11 is fitted into a hole-like portion formed around the shaft core X with respect to the block-shaped member 1, and a straight line is formed along the shaft core X inside the sleeve 11. The spool 12 is inserted and slidably movable, and the valve unit 10 is configured by accommodating a spool spring 13 that applies an urging force to the inner end of the sleeve 11 in the protruding direction (right side in FIG. 1). Yes.

  A bracket 14 is provided outside the block-like member 1 in the sleeve 11, and the fastening bolt 2 described above is inserted into a bolt insertion hole of the bracket 14. The hole-shaped portion, the sleeve 11 and the spool 12 are arranged with a common axis X and a coaxial core.

  Three annular grooves are formed on the outer periphery of the sleeve 11 so as to communicate individually with the supply flow path 1p, the first flow path 1a, and the second flow path 1b. A drain port 11d communicating with the discharge channel 1d is formed at the inner end (left end in FIG. 1) of the sleeve 11.

  In the sleeve 11, a pump port 11 p, a first port 11 a, and a second port 11 b are formed as through-holes in a posture along the radial direction so as to individually communicate with the three annular grooves on the outer periphery. Thus, the pump port 11p communicates with the supply flow path 1p, the first port 11a communicates with the first flow path 1a, and the second port 11b communicates with the second flow path 1b.

  The spool 12 has a pair of land portions 12a formed on the outer periphery, and a drain passage 12b formed coaxially with the shaft core X inside. A drain hole 12d communicating with the internal drain flow path 12b space is formed outside the land 12a on the outer end side (right side in FIG. 1) of the spool 12.

  In this configuration, hydraulic oil is supplied from the hydraulic pump P to a small-diameter region in the middle of the pair of land portions 12a, and the spool 12 is operated along the axis X, whereby the hydraulic oil from the hydraulic pump P is supplied to the first port. 11a and the second port 11b are supplied to one, and the other is discharged to the drain port 11d.

  Further, a cylindrical connecting body 15 connected to the spool 12 and the plunger 21 of the electromagnetic solenoid unit 20 is integrally formed at the end position of the spool 12 on the electromagnetic solenoid unit side. The connecting body 15 may be composed of a member different from the spool 12.

[Electromagnetic solenoid unit]
As shown in FIGS. 1 to 3, the electromagnetic solenoid unit 20 is wound around a bobbin, a plunger 21 disposed coaxially with the shaft core X, a front yoke 22, a rear yoke 23 (an example of a cylindrical member). An exciting coil 24 and a cylindrical case 25 are provided. A connector 26 having a terminal conducting to the exciting coil 24 is provided on the outer surface of the rear yoke 23.

  In the electromagnetic solenoid unit 20, the plunger 21 is arranged coaxially with the shaft core X as described above, and the cylindrical portion of the front yoke 22 and the cylindrical portion of the rear yoke 23 are on the coaxial core with the axial core X. Be placed. The exciting coil 24 is arranged in a region extending between the front yoke 22 and the rear yoke 23 in the direction along the axis X.

  In this configuration, the electromagnetic solenoid unit 20 is held by the sleeve 11 by fitting the fitting portion 22 a formed integrally with the front yoke 22 to the outer end side of the sleeve 11.

  The plunger 21, the front yoke 22 and the rear yoke 23 are made of a magnetic material, and a gap through which magnetic flux acting on the plunger 21 leaks to a portion where the cylindrical portion of the front yoke 22 and the cylindrical portion of the rear yoke 23 face each other. Is formed. In this configuration, when the excitation coil 24 is energized, the plunger 21 is attracted by the magnetic flux leaking from the gap and is linearly operated along the axis X. That is, the position of the gap is set so that a pressing force (force toward the left side in FIG. 1) is applied to the spool 12 by the suction force.

  The plunger 21 is formed with a hole 21 b centered on the shaft core X, and the hole 21 b communicates with the drain flow path 12 b of the spool 12 through the internal space of the connecting body 15. Further, the connecting body 15 connected to the plunger 21 is formed with a through hole 15a that allows the external space and the internal space to communicate with each other. A tapered surface 21 t is formed on the outer periphery of the inner end side (left side in FIG. 1) of the plunger 21.

  In the electromagnetic solenoid unit 20, the rear yoke 23 is formed in a cup shape as a whole, and a housing space S is formed by this cup-shaped space and a space inside the cylindrical portion of the front yoke 22. In the electromagnetic solenoid unit 20, the plunger 21 is disposed in the accommodation space S. With this configuration, the entire plunger 21 is accommodated inside the rear yoke 23.

  In the electromagnetic solenoid unit 20, a part of the hydraulic oil from the valve unit 10 flows into the accommodation space S. However, as described above, the hole 21 b of the plunger 21 communicates with the drain flow path 12 b of the spool 12. The hydraulic oil in the space S can be discharged to the discharge flow path 1d.

[Operating form]
In this electromagnetic valve V, when current (electric power) is not supplied to the electromagnetic solenoid unit 20, the spool 12 comes into contact with the end of the fitting portion 22a of the front yoke 22 by the urging force of the spool spring 13, and is shown in FIG. The first position Pa is maintained.

  Further, by setting the current value (electric power) supplied to the exciting coil 24 of the electromagnetic solenoid unit 20, the spool 12 can be set to the neutral position Pn shown in FIG. 2 against the urging force of the spool spring 13, and the current value is further increased. By doing so, the spool 12 can be set to the second position Pb shown in FIG.

  When the spool 12 is set to the first position Pa shown in FIG. 1, the hydraulic oil from the hydraulic pump P is supplied from the first port 11a to one oil chamber or the like of the hydraulic actuator, and the other oil chamber or the like. From the second port 11b to the drain port 11d. As a result, the hydraulic actuator is operated in a predetermined direction.

  When the spool 12 is set to the neutral position Pn shown in FIG. 2, hydraulic oil is not supplied and discharged from the first port 11a and the second port 11b, so the hydraulic actuator maintains a stopped state.

  Further, when the spool 12 is set to the second position Pb shown in FIG. 3, the hydraulic oil from the hydraulic pump P is supplied from the second port 11b to the other oil chamber or the like of the hydraulic actuator. The hydraulic oil from the chamber or the like is discharged from the first port 11a to the drain port 11d. As a result, the hydraulic actuator is operated in a direction opposite to the predetermined direction described above.

[Plunger surface condition]
The engine oil (hydraulic oil) is mixed with wear powder generated during operation of the engine and is mixed with particulate matter generated during engine combustion. Further, when the plunger 21 is operated in the electromagnetic valve V, the wear powder generated by the wear of the contact portion between the outer peripheral surface 21S of the plunger 21 and the inner peripheral surface 23S of the rear yoke 23 may be mixed into the hydraulic oil. In addition, this outer peripheral surface 21S is an area | region which reaches the outer end in the direction along the axial center X from the site | part used as the largest diameter of the taper surface 21t mentioned above.

  In the electromagnetic valve V, as shown in FIG. 4, particles such as wear powder contained in the hydraulic oil are regarded as foreign matter a, and in a gasoline engine, the particle size G of the foreign matter a is assumed to be about 0.2 μm. In the electromagnetic solenoid unit 20, the plunger 21 can be smoothly operated even when the foreign substance a having a particle size G enters the gap between the outer peripheral surface 21 </ b> S of the plunger 21 and the inner peripheral surface 23 </ b> S of the rear yoke 23. The outer peripheral surface of the plunger 21 is processed.

  That is, as shown in FIGS. 4 and 5 of the present embodiment, the outer peripheral surface 21S of the plunger 21 is recessed with a smooth outer wall region 21Sa having a columnar shape around the axis X and the outer wall region 21Sa as a reference. It is formed of a rough surface area 21Sb having a large number of recesses b. Furthermore, a foreign matter container T is formed in the rough surface region 21Sb.

  In other words, when the plunger 21 is manufactured, the granular projection material collides at high speed with the outer peripheral surface of the columnar base material having the tapered surface 21t and having a preset outer diameter around the shaft core X. Processing by shot peening is performed. In the processing by shot peening, the outer wall region 21Sa is formed in the region where the projection material does not collide, and the rough surface region 21Sb is formed in the region where the projection material collides.

  In particular, in the rough surface region 21Sb, a large number of recesses b are formed on the surface of the base material of the plunger 21 by shot peening. Specifically, the recess b has a spherical inner surface with a diameter D of about 20 μm, and the diameter of particles used for shot peening is set to about 100 μm so that the depth E is about 2.5 μm. In particular, in the plunger 21, the surface roughness of the outer peripheral surface 21S is set to an arithmetic average roughness Ra = 1.0 μm. In other words, the foreign substance accommodating portion T is formed by the plurality of concave portions b, and the depression of the concave portion b with reference to the outer wall region 21Sa is formed in the gap between the outer peripheral surface 21S of the plunger 21 and the inner peripheral surface 23S of the rear yoke 23. It is formed with a depth E larger than the preset particle size G of the foreign matter a entering.

  In shot peening, the projection material may collide with the same position. In such a case, the depth E of the recess b becomes deeper than 2.5 μm. 4 and 5, the depth E is exaggerated with respect to the diameter D. And in the rough surface area | region 21Sb, the foreign material accommodating part T is formed by overlapping the adjacent recessed part b mutually. The foreign substance storage portion T is formed in a form that continues to at least the shaft core X by overlapping at least a part of the plurality of recesses b. Thereby, the foreign material a fitted in the recess b sequentially flows in the adjacent recess b together with the hydraulic oil every time the plunger 21 is operated, and as a result of this flow, one end of the outer peripheral surface 21S in the direction along the axis X. It is discharged outward from.

  In particular, as shown in FIG. 4, in the electromagnetic solenoid unit 20, the distance C between the outer wall region 21Sa of the plunger 21 and the inner peripheral surface 23S of the rear yoke 23 as a cylindrical member is set to a value larger than 0.2 μm. . When the plunger 21 is operated, the outer wall region 21Sa can be operated while being guided by the inner peripheral surface 23S of the rear yoke 23, and a linear operation with high accuracy is realized.

[Performance measurement results]
In FIG. 6, the outer peripheral surface 21S of the plunger 21 is not processed by shot peening or the like, the surface roughness is maintained in a columnar shape with an arithmetic average roughness Ra = 0.09 μm, and the inner peripheral surface 23S of the rear yoke 23 is The structure of the comparative example 1 which made the space | interval C of this slightly larger than the particle size G of the assumed foreign material a is shown.

  In FIG. 7, a rough surface region 21 </ b> Sb having an arithmetic average roughness Ra = 0.15 μm is formed by forming a large number of recesses b by a shot peening technique on a part of the outer peripheral surface 21 </ b> S of the plunger 21. The depth E of b is set to be shallower than the particle size G of the foreign matter a, and the distance C between the rear yoke 23 and the inner peripheral surface 23S (inner wall portion 23Sa) is slightly larger than the assumed particle size G of the foreign matter a. The structure of the comparative example 2 is shown.

  8, 9, and 10, the configurations of Comparative Example 1 (unprocessed), Comparative Example 2 (low surface roughness), and this embodiment (high surface roughness) are supplied to the excitation coil 24. The change of the hydraulic pressure difference (differential pressure) of the hydraulic oil flowing through the first flow path 1a and the second flow path 1b in the control for increasing the power to be increased and the control for decreasing the power is shown in a graph. In these drawings, the spool 12 is operated from the first position Pa to the second position Pb by increasing the current supplied to the electromagnetic solenoid unit 20, and the spool 12 is moved from the second position Pb to the second position by reducing the current. The differential pressure when operating up to 1 position Pa is shown.

  That is, in the electromagnetic valve V having this configuration, since the plunger 21 and the spool 12 operate integrally, when the current value supplied to the excitation coil 24 and the operation amount of the plunger 21 correspond appropriately, the current value The opening degree between the first port 11a and the second port 11b changes in proportion to the increase in the pressure, and the differential pressure between the first flow path 1a and the second flow path 1b is also proportional to the current value.

  For this reason, the operation amount of the plunger 21 corresponding to the current value supplied to the electromagnetic solenoid unit 20 is not measured as the movement distance, but the operation of the plunger 21 is determined from the differential pressure between the first port 11a and the second port 11b. The state can be grasped.

  In Comparative Example 1 (arithmetic mean roughness Ra = 0.09 μm), as shown in FIG. 8, the pressure increase curve i indicating the pressure increase in the second flow path 1b when the current value increases is not smooth. Thereafter, when the current value is reduced, the plunger 21 is operated in the reverse direction by the biasing force of the spool spring 13, but the current value when starting the operation in the reverse direction from the second position Pb is smaller than the predetermined value described above. Therefore, the decompression curve j indicating the pressure drop is not smooth. Further, as shown in FIG. 8, the first hysteresis H1 of the current value is large. Hysteresis is the difference value of the current at the median between the maximum value and the minimum value of the differential pressure shown in FIGS.

  From this result, it can be understood that the foreign substance a contacts the outer peripheral surface 21S of the plunger 21 and the inner peripheral surface 23S (inner wall portion 23Sa) of the rear yoke 23 at the same time to impair the operation of the plunger 21 and the operation of the plunger 21 is not smooth. .

  In Comparative Example 2 (arithmetic mean roughness Ra = 0.15 μm), the same tendency as in the first comparative example is observed, but the boost curve i and the decompression curve j become somewhat smooth as shown in FIG. Since the second hysteresis H2 is small, it can be understood that the operation of the plunger 21 is slightly smooth compared to the first comparative example.

  Further, in the present embodiment (arithmetic mean roughness Ra = about 1.0 μm), as compared with the first comparative example and the second comparative example, as shown in FIG. Since the current value hysteresis Hm is extremely small, it can be understood that the operation of the plunger 21 is smooth.

  In particular, FIG. 11 shows the relationship of the hysteresis of the current value when the deteriorated hydraulic fluid is used in the first comparative example, the second comparative example, and the present embodiment (the first hysteresis H1, the second hysteresis H2, Hysteresis Hm) is shown, and it can be understood from the figure that the configuration of the present embodiment operates most smoothly.

  In this electromagnetic valve V, the excitation coil 24 is energized to set the neutral position Pn. Therefore, in the case where the foreign matter container T is formed on the surface of the plunger 21, the first position Pa is set to the neutral position Pn. Therefore, there is no large difference in the current value supplied to the exciting coil 24 in any case between the case where the second position Pb is set to the neutral position Pn, and high-precision control is possible.

[Operation / Effect of Embodiment]
Even if degraded hydraulic oil containing a large amount of foreign matter a is used, the foreign matter a existing on the outer peripheral surface 21S of the plunger 21 is caused by the flow of hydraulic oil accompanying the operation of the plunger 21. Therefore, the plunger 21 is discharged from the end in the direction along the axis X of the plunger 21. Thereafter, the hydraulic oil containing the foreign matter a passes through the drain passage 12b from the hole 21b and is discharged to the outside from the drain port 11d. Thereby, the inconvenience that the foreign substance a remains on the outer peripheral surface 21S of the plunger 21 is eliminated, the sliding resistance of the plunger 21 is reduced, and a smooth operation is always possible.

  In this electromagnetic valve V, the depth E of the rough surface region 21Sb is set in accordance with the particle size G of the foreign matter a, and the outer wall region 21Sa of the plunger 21 and the inner peripheral surface 23S of the rear yoke 23 as a tubular member. Set the interval C. Therefore, for example, in the case of generating carbon particles as foreign matter a at the time of combustion like a diesel engine, it is possible to set the depth E and the interval C corresponding to the particle size G of the foreign matter a of the carbon particles. Thus, smooth operation of the electromagnetic valve V is realized by this setting.

  In this embodiment, the projection 21 is projected on the outer peripheral surface 21S of the base material of the plunger 21 by shot peening to form the rough surface area 21Sb, and the area where the projection material does not collide is the outer wall area 21Sa. The rough surface region 21Sb and the outer wall region 21Sa can be easily formed by setting the time for performing peening. Furthermore, by performing shot peening, the hardness of the surface of the plunger 21 is improved by the residual stress imparting effect, and the wear resistance can be improved.

[Another embodiment]
In addition to the above-described embodiments, the present invention may be configured as follows (the components having the same functions as those of the embodiments are given the same numbers and symbols as those of the embodiments).

(A) As shown in FIG. 12, the electromagnetic solenoid unit 20 includes a plunger 21 disposed coaxially with the shaft core X, a cup-shaped member 31 (an example of a cylindrical member) that accommodates the plunger 21, and a coil holding A portion 32, an exciting coil 24 wound around a bobbin, and a cylindrical case 25 are provided.

  In this configuration, the cup-shaped member 31 is made of a nonmagnetic metal such as stainless steel, a copper alloy, or an aluminum alloy, and the coil holding portion 32 is made of a nonmagnetic resin. Further, the excitation coil 24 and the plunger in the direction along the axis X so that the plunger 21 exerts a pressing force (force toward the left side in FIG. 12) on the spool 12 by a magnetic field generated when the excitation coil 24 is energized. The relative positional relationship with 21 is set.

  Even in the configuration of this another embodiment (a), the outer wall surface 21Sa and the rough surface region 21Sb described in the embodiment are formed on the outer peripheral surface 21S of the plunger 21, and the outer peripheral surface 21S and the inner periphery of the cup-shaped member 31 are formed. Appropriate operation of the plunger 21 is enabled by appropriately setting the distance from the surface 31S.

(B) In the embodiment, the rear yoke 23 is configured as a cylindrical member in order to apply a pressing force to the spool 12 by energizing the excitation coil 24 to actuate the plunger 21 inward. When the coil 24 is energized, a force may be applied to the spool 12 in the pulling direction by operating the plunger 21 outward. In such a configuration, since the plunger 21 is arranged inside the front yoke 22, the front yoke 22 becomes a cylindrical member.

(C) The electromagnetic valve V is for setting the spool 12 to 3 positions. For example, the solenoid valve V may be configured to set the spool 12 to 2 positions or to be set to 3 positions or more.

(D) The foreign material container T is formed by knurling the base material of the plunger 21 of the electromagnetic solenoid. Even if processed in this way, the outer wall surface 21Sa and the rough surface region 21Sb described in the embodiment are formed on the outer peripheral surface 21S of the plunger 21, and the smooth operation of the plunger 21 is realized. .

  INDUSTRIAL APPLICATION This invention can be utilized for the electromagnetic solenoid which act | operates the plunger inserted by the cylindrical member by supplying with electricity to an exciting coil.

20 Electromagnetic solenoid unit (electromagnetic solenoid)
21 Plunger 21S Outer peripheral surface 21Sa Outer wall region 21Sb Rough surface region 22S Inner peripheral surface 23 Rear yoke (tubular member)
24 Excitation coil 31 Cup-shaped member (tubular member)
a Foreign object b Recessed part D Diameter E Depth G Particle size T Foreign substance containing part X Axle

Claims (5)

A tubular member, a plunger made of a magnetic material disposed movably along the axial center of the tubular member inside the tubular member, and a magnetic force acting on the plunger to move the plunger to the shaft of the tubular member An excitation coil that operates along the core,
The outer peripheral surface of the plunger has a cylindrical outer wall region centering on the axis of the plunger, and a rough surface region composed of a large number of recesses recessed with respect to the outer wall region.
The recess has a spherical inner surface with a predetermined diameter, and at least a part of the plurality of recesses is formed to overlap, so that the recess of the recess with respect to the outer wall region is an inner periphery of the cylindrical member. An electromagnetic solenoid formed as a foreign matter container having a depth larger than a preset particle size of foreign matter entering a gap between the surface and the outer peripheral surface of the plunger.   2. The electromagnetic solenoid according to claim 1, wherein the foreign substance accommodating portion reaches at least one end portion of the plunger by being continuous in at least a direction along the axis.   The electromagnetic solenoid according to claim 1 or 2, wherein a gap between an inner peripheral surface of the cylindrical member and the outer wall region of the plunger is set larger than the particle size. A tubular member, a plunger made of a magnetic material disposed movably along the axial center of the tubular member inside the tubular member, and a magnetic force acting on the plunger to move the plunger to the shaft of the tubular member An electromagnetic solenoid is configured with an excitation coil that operates along the core,
Due to shot peening of the base material, the plunger does not collide with the projecting material, and the outer wall region is a columnar shape centering on the axis of the plunger, and the projecting material collides with the outer wall region to make a large number of depressions. A rough surface region having a concave portion, and formed on the outer surface,
A method of manufacturing an electromagnetic solenoid in which a foreign matter container is formed by overlapping at least some of the plurality of recesses.   5. The electromagnetic wave according to claim 4, wherein the foreign substance accommodating portion reaches at least one end of the plunger by forming the adjacent concave portions so as to be aligned at least in a direction along the axis. Solenoid manufacturing method.

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